doc: say the sha256 compression callback processes secrets #1963

pull fametrano wants to merge 1 commits into bitcoin-core:master from fametrano:doc-sha256-compression-secrets changing 1 files +3 −0

fametrano commented at 7:04 AM on October 12, 2026: contributor

As agreed in #1958, this notes in the header that the callback sees secrets such as secret keys, so it must run in constant time and must not keep or log its input.

Fixes #1958.

Assisted-by: my usual tools (LLM, Internet, computer). Mistakes are mine.

doc: say the sha256 compression callback processes secrets

The function set by secp256k1_context_set_sha256_compression hashes
secret keys, for example when deriving RFC 6979 nonces. Say so, and
require it to run in constant time and not to keep or log its input.

Fixes #1958.

Assisted-by: my usual tools (LLM, Internet, computer). Mistakes are mine.
Signed-off-by: Ferdinando Ametrano <ferdinando@ametrano.net>

494d3053c0

real-or-random approved
real-or-random commented at 7:58 AM on October 12, 2026: contributor

ACK 494d3053c0cb4d28c7015a088f8c6270063fd017
real-or-random added the label user-documentation on Oct 12, 2026
real-or-random added the label side-channel on Oct 12, 2026
real-or-random added the label tweak/refactor on Oct 12, 2026
furszy commented at 1:45 PM on October 12, 2026: member

utACK 494d3053c0cb4d28c7015a088f8c6270063fd017
theStack approved
theStack commented at 7:34 PM on October 12, 2026: contributor

ACK 494d3053c0cb4d28c7015a088f8c6270063fd017

Thanks! Small commit message nit for future contributions: we usually don't use the "Assisted-by:" tag, and I don't think a generic one mentioning "usual tools" conveys useful information.
theStack merged this on Oct 12, 2026
theStack closed this on Oct 12, 2026
real-or-random commented at 6:19 AM on October 13, 2026: contributor

Small commit message nit for future contributions: we usually don't use the "Assisted-by:" tag, and I don't think a generic one mentioning "usual tools" conveys useful information.

Also, while the "Signed-off-by:" line doesn't hurt, it carries no meaning in this project. ("Signed-of-by:" is used by some projects such as the Linux kernel. It's supposed to certify that contribution complies to some legal requirements specified in a project-specific document, but we don't have such a document.)

Contributors

Labels

user-documentation side-channel tweak/refactor

Linked (view graph)

#1958 Document that the sha256 compression override sees secret keys